Machines are known which comprise two cutters which have a trapezoidal section and are inclined to the vertical and rotatively mounted on a frame adapted to be coupled to a platform, these cutters effecting digging of ditches having a trapezoidal cross-sectional shape.
Machines are also known for digging which have a single wheel or cutter in the shape of a double truncated cone which also produce ditches having inclined walls. These machines, whose cutters are driven by the power take-off of the tractor or by hydraulic motors, only permit the production of relatively shallow ditches or the cutting of the ditch in a plurality of successive passes, which constitutes a considerable loss of time and energy.
Further, both in machines having two inclined cutters and those having a single cutter, the relative position and the shape of the tools determine the profile of the ditch produced without the possibility of modifying this profile.